The unidentified patient, who played while in bed, sought medical help after noticing swelling and pain in his legs. Doctors found that he had deep vein thrombosis and had multiple blood clots in his legs.

Deep vein thrombosis usually occurs when a person is sedentary or still for long periods of time and can lead to a life-threatening pulmonary embolism if a blood clot forms in the leg and travels to the lung.

The man in the case study, an exterior painter, first noticed symptoms into his second day of game playing but didn’t seek medical attention for another 48 hours, according to the report. In spite of the delay in treatment, doctors were able to dissolve the clots with medications.

As people spend more and more time playing video games, some experts are now concerned that there could be a rise in cases of deep vein thrombosis. The authors of the case study recommended further research to study the effects of game playing on the body.

Experts say that unlike television or other sedentary activities, video games encourage people to stay still to finish a game.

“One thing about video games is it requires that you’re doing things and attending to it,” said Joe Hilgard, a doctoral candidate at the Department of Psychological Sciences at University of Missouri. "It can be harder to walk around the room than say if you were watching T.V.”

Additionally, Hilgard said that playing the game could have helped the patient ignore his symptoms.

“There’s something about games that’s a little anesthetic,” said Hilgard, who points out video games are sometimes used to soothe children in the hospital because the games can distract players.

Cardiologists say cases where a person appears to suddenly develop blood clots on a long-distance flight or other common activity such as playing video games, it often indicates that the person had secondary risk factors.

Dr. Gregory Piazza, a cardiologist at Brigham and Women’s Hospital in Boston, said risk factors such as smoking, taking birth-control pills or having hormonal problems can lead to greater risks of developing pulmonary embolisms.

To avoid deep vein thrombosis, people should avoid being sedentary and be sure to move around if they are on a long flight. Piazza said people should also listen to their body so that they can seek treatment early if they have symptoms.

“It’ll be a few a days before they interpret the symptoms as something they need to see a health care provider for,” said Piazza. “They may think it’s attributable to sleeping in the wrong position. ... It’s only after the symptoms persist” that they seek a doctor.

Common symptoms for deep vein thrombosis include swelling of the leg, pain in the lower or upper extremities or feeling like one shoe is too tight, Piazza said.